title: GSTP1 Ile105Val polymorphism and colorectal cancer risk: an updated analysis.
abstract: BACKGROUND
  Many studies have investigated the association between the Glutathione S transferase-P1 (GSTP1) Ile105Val polymorphism and colorectal cancer (CRC) susceptibility, but the results were conflicting. The aim of this study is to quantitatively summarize the relationship between this polymorphism and CRC risk.
  
  
  METHODS
  Two investigators independently searched the Medline, Embase, China National Knowledge Infrastructure (CNKI) and Chinese Biomedicine databases for studies published before December 2012. Summary odds ratios (ORs) and 95% confidence intervals (95% CIs) for GSTP1 polymorphism and CRC were calculated in a fixed-effects model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate.
  
  
  RESULTS
  This meta-analysis included 29 case-control studies, which included 8160 CRC cases and 10,450 controls. Overall, the variant genotypes (ValVal and IleVal) of the Ile105Val were not associated with CRC risk when compared with the wild-type IleIle homozygote. Similarly, no associations were found in the dominant and recessive models. When stratifying for ethnicity, source of controls, study sample size and genotyping methods, no evidence of significant association was observed in any subgroup, except among those studies taking others as genotyping methods (recessive model, OR=0.71, 95%CI=0.52-0.96). Limiting the analysis to the studies within Hardy-Weinberg equilibrium, the results were persistent and robust. No publication bias was found in the present study.
  
  
  CONCLUSIONS
  This updated meta-analysis suggests that the GSTP1 Ile105Val polymorphism may not be associated with CRC risk, while the observed decrease in risk of CRC may be due to small-study bias.
authors.affiliation: Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu 610041, Sichuan Province, PR China.
authors.forename: Zhibo
authors.initials: Z
authors.lastname: Tan
authors.forename: Mei
authors.initials: M
authors.lastname: Feng
authors.forename: Yangkun
authors.initials: Y
authors.lastname: Luo
authors.forename: Chuntang
authors.initials: C
authors.lastname: Sun
authors.forename: Zixuan
authors.initials: Z
authors.lastname: Fan
authors.forename: Yan
authors.initials: Y
authors.lastname: Tan
authors.forename: Binyu
authors.initials: B
authors.lastname: Fu
authors.forename: Jinyi
authors.initials: J
authors.lastname: Lang
mesh_terms: D019943:Amino Acid Substitution; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000235:genetics*; D005787:Gene Frequency; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D051549:Glutathione S-Transferase pi / Q000235:genetics*; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
chemical_list: C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi
keywords: CI; CRC; Colorectal cancer; GSTP1; Glutathione S transferase-P1; HWE; Hardy–Weinberg equilibrium; Meta-analysis; OR; Polymorphism; SNP; colorectal cancer; confidence interval; odds ratio; single nucleotide polymorphisms